The prior art approach to manufacturing sheet metal details, such as for manufacturing airplane components, includes issuing rectangular sheets of raw stock. In order to stretch form the sheet metal using National Aerospace Standard (NAS) 930, "stretch forming machines--airframe", for manufacturing an airplane component, such as a wing, excess material is required around the periphery of the sheet for sheet forming. The raw stock is stretch formed across a tool, then the raw stock is relaxed after forming, removing most of the force (load) from the sheet stock, then an operator employs one of several methods to index the stock to the tool. For indexing, drilled or punched holes establish the periphery of the sheet that is stretch formed to the contour. Usually these holes require an additional drilling operation outside the stretch form press. The holes are used to index the sheet to a second tool used for trimming the sheet to the desired periphery configuration.
The trimming operation may comprise hand routing, pin routing, shaping, blanking or routing with numerical controlled equipment. These are all operations separate from the stretch press operation, therefore, requiring additional steps and additional tools. Hand routing, for example, requires a template style tool and a hand-held router with cutting bits. Blanking requires a blanking die and a press to perform the blanking. Trimming with numerical controlled equipment can sometimes be performed without another tool, but the equipment is expensive and requires programming by qualified individuals. Therefore, it still requires another operation, even when additional tooling is not necessary.
It is desirable to provide a method and apparatus for forming and shearing a sheet metal workpiece in which the tooling requirements are minimized and the number of operational steps are minimized.